Japanese Unexamined Patent Publication No. 8(1996)-241776 discloses an example of an IC socket, which is used in electronic devices, such as personal computers. The IC socket comprises two types of sideways facing U-shaped contacts, which are mounted in a housing by base portions thereof. One end of each of the contacts is mounted in the housing, and the other end of the contact is formed as a contact arm for contacting an IC package. The two types of contacts are of different sizes, and the contact arms are arranged such that the contact arms overlap each other.
Japanese Unexamined Patent Publication No. 7(1995)-282931 discloses another example of an IC socket. The IC socket includes contacts that extend substantially linearly in a horizontal direction and are alternately provided in a housing by leg portions thereof. Contact portions are formed where the contacts and electrodes of an IC package connect and are formed at ends of the horizontally extending portions of the contacts in an upwardly facing manner.
In the IC socket disclosed in Japanese Unexamined Patent Publication No. 8(1996)-241776, it is difficult to arrange the contacts in a matrix and at a high density, because of the horizontally extending contact arms. In the IC socket disclosed in Japanese Unexamined Patent Publication No. 7(1995)-282931, it is also difficult to arrange the contacts in a matrix and at a high density, because the contacts extend in the horizontal direction.
In both of the IC sockets described above, the contact portions that contact electrodes of an IC package protrude upward. Therefore, there is a possibility that external objects, such as fingers, will contact the exposed contact portions during mounting or dismounting of the IC package onto the IC socket. Because the mounting and dismounting of the IC package is performed by hand, the possibility of this type of damage occurring is great. In the case that a finger or the like contacts the contact portions, external force is applied thereto, which may cause plastic deformation of the contact portions. If the contact portions are deformed, there is a possibility that electrical connections will not be established between the IC package and the contacts of the IC socket.
In an effort to address this problem, contacts having relatively large curved portions at tips thereof have been developed to reduce the likelihood that external objects will deform the contacts. FIG. 10 is a sectional view of a contact portion 162 of a conventional contact 156 having such a configuration. The contacts 156 are mounted within contact receiving openings 154 of an insulative housing 152. Contact arms 158 of the contacts 156 protrude upward from an upper surface 160 of the housing 152. The contact portions 162 formed at tips of the contact arms 158 have upwardly convex curved portions 163 for contacting electrodes (not shown) of an IC package (not shown). Tips 162a of the contact portions 162 curve toward the insulative housing 152 so that external objects are prevented from engaging the contact portions 162 and deforming the contact arms 158.
In the conventional contact illustrated in FIG. 10, the tips 162a of the contact portions 162 are bent such that the tips 162a curve downward. It is therefore difficult to provide sufficient space in a vertical direction of the housing 152 such that the contact portions 162 do not interfere with the adjacent contacts 156. There is therefore a possibility that the tips 162a of the contact portions 162 will contact the contact arm 158 of the adjacent contacts 156 when the contact arms 158 are flexed by the electrodes (not shown) of the IC package (not shown), thereby shorting the connection there between. Because it is difficult to arrange the contacts 156 such that the contacts 156 overlap and such that the positions of the contacts 156 are shifted so that the contact arms 158 do not interfere with each other even when flexed, this type of configuration causes the arrangement pitch of the contacts 156 in the horizontal direction to be great. It is therefore difficult to make high density arrangements of the contacts 156. Additionally, because the contacts 156 are exposed from the housing 152, there is a possibility that the contacts 156 will become damaged or soiled when touched by the external objects. If the contacts 156 become damaged or soiled, the reliability of the electrical connections established thereby can be reduced.